Abstract: A dual frequency laser amplifier includes a beam generator for generating first and second source laser beams, and a co-doped optical fiber including first and second dopant ions having first and second gain bandwidths corresponding to the respective wavelengths of the first and second source laser beams for selectively forming first and second diffraction limited output laser beams responsive to the relative radiated power between the first and second source laser beams. A dual frequency laser oscillator and a method for generating the first and second output laser beams at any predetermined radiated power distribution are also described.

Abstract: An optical fiber amplifier which receives a primary laser beam and generates a coherent amplified laser beam, includes an optical isolator which transmits the primary laser, a 3-dB coupler which receives the primary laser beam, which generates first and second laser beams, which receives first and second amplified laser beams, and which combines the amplified laser beams to thereby produce the coherent amplified laser beam, a phase controller operatively connected in parallel with the 3-dB coupler which controls the phase of each of the amplified laser beams, and first and second fiber amplifiers operatively connected to the 3-dB coupler, the fiber amplifiers receiving first and second laser beams and generating the amplified laser beams, respectively. A high power coherent laser amplifier utilizing several optical fiber amplifier networks connected to one another in parallel is also described.

Abstract: A battlefield personnel threat detection system for identifying and analyzing vibrations corresponding to an immutable characteristic of a target of interest includes a transmitter for producing a transmit laser beam by amplification of a primary coherent laser signal, a coherent receiver responsive to backscattered light produced by interaction of the transmit laser beam with the target of interest and generating data corresponding to the immutable characteristic of the target of interest, and a control and display module for analyzing the data to thereby detect the presence of the target of interest and for controlling operation of the transmitter and the receiver. The target of interest can be an enemy soldier.

Abstract: A method for compensating a reference signal used in a coherent receiver of a micro-doppler sensor having a transmitter includes the steps for: (a) repeatedly measuring phase differences between a signal emitted by the transmitter a first time and a previous signal emitted at a previous time so as to produce a plurality of phase error signals; (b) accumulating the phase error signals over a propagation time between the transmitter and the coherent receiver so as to produce a cumulative phase error signal; and (c) modulating a signal produced by the transmitter at the end of the propagation period so as to generate a compensated reference signal having a phase characteristic substantially identical to the signal produced by the transmitter at the beginning of the propagation period. A phase error or noise compensator, which can form part of a micro-doppler ladar system, is also described.

Abstract: A micro-doppler ladar system for identifying and analyzing a target of interest includes a transmitter and coherent receiver pair, each of which includes a fiber optic power amplifier, and a controller. Preferably, the transmitter includes a master oscillator for generating a primary laser beam, a voltage controlled oscillator (VCO) for generating a VCO signal having a predetermined, repetitive frequency pattern, a frequency shifting circuit for varying the frequency of the primary laser beam responsive to the VCO signal to thereby produce a frequency-varying primary laser signal, and the optical fiber amplifier, which amplifies the frequency-varying primary laser signal to thereby produce a transmit laser beam.

Abstract: An electron beam pumped semiconductor laser which includes a substrate, an optical gain structure provided on the substrate, the optical gain structure being comprised of a plurality of alternating quantum well layers and isolation layers, the quantum well layers being spaced apart from one another by respective, intervening ones of the isolation layers by a sufficient distance to substantially isolate the quantum well layers from one another, and a first reflective layer provided on a first surface of the optical gain structure. With this construction, the quantum well layers are quantum mechanically uncoupled. Further, the optical gain structure has a total thickness which is sufficient to enable the optical gain structure to be coupled to excitation of an electron beam produced by an electron beam pumping device and directed through the first reflective layer and incident upon the optical gain structure.

Abstract: A phased array Raman laser amplifier includes a beam generator for generating a fundamental laser beam and a Raman seed frequency laser beam, and a fiber optic laser amplifier array for forming a diffraction limited output laser beam at the Raman seed frequency by amplifying the fundamental laser beam to a power level corresponding to the Stimulated Raman Scattering (SRS) threshold to thereby pump the SRS process and provide Raman gain to the Raman seed frequency laser beam.

Abstract: An electron beam pumped semiconductor laser includes a semiconductor laser screen and an electron beam source adjacent the semiconductor laser screen. The semiconductor laser screen comprises a transparent single crystal substrate, an electron beam responsive active gain layer on the substrate, and first and second reflective layers. The epitaxial electron beam responsive active gain layer has a crystal structure in alignment with the crystal structure of the substrate, and the first and second reflective layers define a laser cavity through the epitaxial electron beam responsive active gain layer therebetween. The electron beam source generates an electron beam which impinges on the epitaxial electron beam responsive active gain layer thereby generating a laser output. Accordingly, the single crystal active gain layer can be formed on the substrate by epitaxial deposition techniques increasing the performance and reliability of the electron beam pumped semiconductor laser.

Abstract: A three-dimensional (3-D) virtual display system for displaying a flicker-free 3-D virtual image to each of N viewers randomly dispersed about a horizontally disposed viewing screen, where N is an integer greater than 1, includes a laser projector for generating N.times.M image pairs responsive to a video signal comprising the N.times.M image pairs, N transmitters associated with respective ones of the N viewers, each of the N transmitters generating a unique coded pulse, a detector for determining the position of each of the N viewers relative to the viewing screen responsive to the respective unique coded pulse and for generating respective position data, a graphics processor for generating the video signal responsive to the position data, and N selectors associated with the N viewers for selecting the M image pairs out of the N.times.M image pairs allocated to each of the N viewers, respectively. The projector includes an electron-beam-pumped semiconductor laser (EBSL) screen, e.g.

Abstract: A direct diode laser system includes N laser head assemblies (LHAs) generating N output beams, N optical fibers receiving respective N output beams and generating N received output beams, and a torch head recollimating and focusing the N received output beams onto a single spot. Preferably, each of the laser head assemblies of the direct diode laser system includes M modules generating M laser beams, wherein each of the M laser beams has a corresponding single wavelength of light, M-1 dichroic filters, wherein each of the M-1 dichroic filter transmits a corresponding one of the M laser beams and reflects all other wavelengths, and a fiber coupling device collecting the M laser beams to produce a respective one of the N output beams. In an exemplary case, the M-1 dichroic filters function as band pass filters. A method of generating a high fluence, high power laser beam is also described.

Abstract: The fiber optic laser system and associated lasing method amplifies and divides a primary laser signal into a plurality of secondary laser signals. The fiber optic laser system includes a distribution means, such as a distribution module, for dividing a primary laser signal, generated by a master oscillator into a number of secondary laser signals. The distribution module can include amplification means, such as an optical fiber amplifier, for amplifying the primary laser signal and a signal power splitter for dividing the amplified primary laser signal into a number of secondary laser signals. The secondary laser signals can then be further amplified, such as by a power amplification module including another optical fiber amplifier. The secondary laser signals can be recombined to produce a laser output having a power level greater than the predetermined power level of the primary laser signal.

Abstract: An electron beam pumped semiconductor laser includes a semiconductor laser screen and an electron beam source adjacent the semiconductor laser screen. The semiconductor laser screen comprises a transparent single crystal substrate, an electron beam responsive active gain layer on the substrate, and first and second reflective layers. The epitaxial electron beam responsive active gain layer has a crystal structure in alignment with the crystal structure of the substrate, and the first and second reflective layers define a laser cavity through the epitaxial electron beam responsive active gain layer therebetween. The electron beam source generates an electron beam which impinges on the epitaxial electron beam responsive active gain layer thereby generating a laser output. Accordingly, the single crystal active gain layer can be formed on the substrate by epitaxial deposition techniques increasing the performance and reliability of the electron beam pumped semiconductor laser.

Abstract: An immersion cooled semiconductor laser assembly includes an electrically activated semiconductor laser device, such as a two-dimensional laser diode array, and liquid coolant flowing thereabout which directly contacts the emitting facet of the semiconductor laser device. The semiconductor laser assembly also includes first and second electrodes for supplying electrical energy to the semiconductor laser device such that the semiconductor laser device emits a laser output through its emitting facet. During the emission of the laser output, however, the semiconductor laser device generates heat, thereby increasing the temperature of the semiconductor laser device. In order to protect the semiconductor laser device, the circulating liquid coolant draws heat from the semiconductor laser device, thereby cooling the semiconductor laser device.

Abstract: A semiconductor active waveguide optical crossbar switch to allow optical signals to be routed to any number of ports with no net attenuation of signal strength. The optical crossbar switch is comprised of a network of optical waveguides wherein both lateral and transverse carrier confinement is provided. Redirection of the optical waveguide is accomplished by means of total internal reflectance turning mirrors. Furthermore, the optical waveguides are formed such that electrical current may be applied to the semiconductor structure to amplify the optical signal travelling therein. Electro-absorption switches formed from distinct metallic contacts overlying portions of the optical waveguides amplify the optical signal travelling through the waveguide underneath the switch if sufficient electrical stimulation is applied to the switch.

Abstract: There is provided by this invention an optical heterodyning device comprised of a semiconductor heterostructure having a forward biased electrode connected thereto for optically mixing an input signal frequency with a local oscillating frequency in the separate confined laser cavity and a reverse biase electrode connected thereto for detecting the intermediate frequency produced. The local oscillator provides preamplification in the laser cavity and can be effectively phase locked to the input signal frequency.

Abstract: A linear array of multimode laser diodes in a single wafer having a ratio of approximately one emitting stripe width to each non-emitting stripe isolation region width exhibits transverse lasing in a direction perpendicular to the normal laser output at input currents above a pre-determined transverse lasing threshold. Above the transverse lasing threshold, normal lasing is rapidly quenched.

Abstract: A laser diode array produces one set of beams that are out of phase with those of another set of beams, with the beams of one set alternating with those of the other. The phase plate has first and second sets of regions, with the regions of one set alternating with those of the other. The phase plate is positioned in the near field of the beam pattern such that one set of beams passes through one set of regions and the other set of beams passes through the other set of regions. One set of regions changes the phase of the beams passing therethrough to create a substantially single lobed beam pattern in the far field.

Abstract: The low voltage operation of this electro-optic modulator is realized by a unique system configuration in which the input light beam is first separated into two linearly polarized components of equal intensity, the beams are then focused into two crystals where the beams propagate as pure E waves, the crystals are electrically modulated and the output beams from each crystal are then recombined and recollimated. The low voltage operation is rendered possible by the fact that there is no cancellation between the E and O components as in conventional modulation systems of this type since both beams are transmitted as pure E waves during the modulation process.

Abstract: A laser diode suitable for integrated and fiber optic applications requiring single transverse and single longitudinal mode operation. The single transverse mode is provided by making a gallium arsenide double heterostructural laser diode with a narrow stripe width and a relatively long length. The single longitudinal mode operation is provided by cracking the diode transverse to the stripe at one or more locations to form internal etalons in the laser cavity.

Abstract: A solid state laser rod and a mount through which heat is dissipated from the rod are joined together at a bond comprised of a reflective layer on the surface of the rod, a barrier layer over the reflective layer, and a solder layer between the barrier layer and the mount. The reflective layer may be applied by sputter or other deposition procedures and is highly reflective in the region of the spectrum at which the laser operates, thus insuring optimum efficiency for the rod. The barrier layer may be applied to the reflective layer by the same deposition procedure, and it is impervious to the solder so that the solder does not penetrate it and scavenge the reflective layer. The solder should have a low melting point so as to avoid setting up excessive mechanical stresses in the rod when the solder solidifies. Both the mount and the barrier layer may be covered with a wetting layer prior to soldering to achieve better adhesion of the solder.